Non-Destructive Bridge Testing With Advanced Micro-II Digital AE system

The Eastern Seaboard Intermodal Transportation Applications Center (ESITAC) at Hampton University, with its stated goals to utilize University resources in partnership with state and city governments, local transit companies, private industries, and regional universities, aims to conduct research on current transportation problems facing Hampton Roads, and to advance U. S. technology and expertise that will provide safe, secure, efficient, and interconnected transportation systems. These goals incorporate U. S. DOT's stated priority for improving the safety of the nation's highway bridges. Research on and utilization of non-destructive test (NDT) and monitoring technologies for bridge safety is one of the focus areas in ESITAC's strategic planning. During the research period of January 1 - December 31, 2009, two bridges were identified as potential test candidates for NDT using the acoustic emission (AE) technology: 1. the bridge on I-164 at the Coast Guard Blvd. in the City of Portsmouth (built in 1991) that has an average daily traffic of 22,276 with 4% truck traffic according to the latest data in comparison to an average daily traffic of 11,337 with 4% truck traffic in 2004; and 2. a bridge located in the city of Williamsburg (Virginia Department VDOT Display structure 018 - 1917 (built in 1939) that has an average daily traffic of 2230 but with 5% daily average of truck traffic. Metal and non-metal bridge structure components were investigated using NDT of acoustic emission (AE) with the objective to monitor health of these bridges in collaboration with VDOT's District Structure and Bridge Engineering Department. It was proposed to develop accurate, reliable and durable NDT methods of structural health monitoring of highway bridges to help prevent spread of structural failures. In view of the changes made in the VDOT display structure 018 - 1917, research was focused on the bridge on I-164 situated near a cargo terminal at the Coast Guard Blvd. in the City of Portsmouth with the objective to investigate bridge structure element ACTIVE defects during periods of low and/or no traffic and peak and/or heavy traffic in short areas of the AE sensors. Hence, the study focused on areas with higher potential of damage. Discussions were held with the VDOT/Virginia Transportation Research Council (VTRC) bridge engineers to finalize a plan of action to utilize AE sensors on the potential inspection sites, both on the Suffolk bound and Norfolk bound lanes of the Interstate. Potential test sites were identified based on the results from a monitoring system consisting of 2 AE sensors and the data acquisition (DAQ) system. The following has already been achieved during this period: * Potential sites for monitoring and for analyzing AE were identified. * An 8 sensor system for monitoring the test sites has been designed. * Integration of the existing 4 channel hardware with the newly acquired AE system. * The newly designed AE monitoring system is based on 12V rechargeable batteries and inverters. * The DAQ, computerization and power systems are designed for their operational capability under conditions of unavailability of power. * The designed equipment is under fabrication and is being acquired by ESITAC with RITA approval. The following is being proposed for the period of 2010: * To continue studies on Virginia bridges (i.e. Figure 1) using the newly acquired 8 channel AE sensor and DAQ system. * AE monitor both the metal and non-metal (e.g. concrete) bridge structural components. * Analyze the AE data in a linear and 2D framework to locate the damages including in areas where accessibility is a challenge for the inspection team. * Establish an bridge inspection procedure and methodology based on the studies during quiet/low and peak traffic periods. * Investigate the role of thermal factors and incorporate in the inspection procedure. * Monitor, record and analyze the AE data on a near real time basis.  This proposed research on the bridge at the Coast Guard Blvd. in the City of Portsmouth is tentatively planned to commence in March, 2010 and conclude in December, 2010. The major elements of the work are shown below along with the expected start and finish dates. * Research Preparation: review of the updated status of the bridge monitoring based on the database from VDOT (MAR 2010 - APR 2010) * Data collection (MAY 2010 - AUG 2010) * Analysis of Results (SEP 2010 - OCT 2010) * Prepare and submit the final report (NOV 2010 - DEC 2010)